Power seat adjusters are a popular option on many automotive vehicles and are frequently offered as standard equipment on higher priced vehicles. Such power seat adjusters are primarily used on the driver's seat and, sometimes, on the front passenger seat of the vehicle.
Such power seat adjusters carry an upper support frame which supports the seat bottom and sometimes the seat back of the vehicle seat. The upper support frame is mounted in first and second, spaced track assemblies, each formed of an upper track which is connected to the upper support frame and which is slidably mounted in a lower track anchored to the vehicle floor. A drive mechanism, typically formed of a bi-directional electric motor mounted on the power seat adjuster rotates a pair of drive shafts extending outward from the motor to a gear assembly mounted in each upper track. In one arrangement, the gear assembly rotates a lead screw extending below each upper track. A drive block mounted to the lower track threadingly receives the lead screw to cause reciprocal movement of the upper track and the attached upper support frame upon selective energization of the drive motor.
As the various drive motors are mounted between the track assemblies, the drive motor output shaft and the drive shaft connected thereto are typically oriented perpendicularly to the axis of the associated lead screw. In order to transmit rotation and drive force between the output shaft of the drive motor and the drive shaft connected thereto to the 90.degree. of set lead screw, each gear assembly typically includes a worm gear which is insert molded on one end of the associated lead screw. A worm is rotatably mounted in the gear assembly housing in meshing-engagement with the worm gear and is connected to one of the drive motor output shafts or to one of the drive shafts so to rotate the worm gear and thereby the lead screw upon bi-directional energization of the selective drive motor. Thus, each drive motor requires a separate gear assembly for each lead screw driven by the drive motor.
In particular, the horizontal drive mechanism employed to reciprocally move each upper track within a lower track typically includes a gear assembly attached to the upper track and coupled to the output shaft of a horizontal drive motor to transmit rotation of the output shaft of the drive motor to rotation of the lead screw which, through threading interaction with the drive block attached to the lower track results in a sliding movement of the upper track with respect to the associated lower track.
The metal to metal contact of the gears may generate undesirable noise and can create vibrations which are transmitted through the metal components of the power seat adjuster directly to the user of the seat. In addition, the worm within the housing of the assembly may further enhance the noise vibration by its lateral movement within the housing. To alleviate the noise resulting from lateral movement of the worm within the housing, a set screw was externally attached to the housing at one of the open ports to the worm. The set screw eliminated lateral movement of the worm, but at the same time prevented access for adjustment or attachment to the worm at that port.
It is desirable to provide a gear assembly for a power seat adjuster which minimizes noise and vibrations generated by lateral movement of the worm in the gear housing. It is further desirable to provide a bearing device for a journal of the worm such that an exterior access is provided to the worm. It is also desirable to provide a device that allows access for an adjustment to remove lateral movement in the worm. Finally, it is desirable to provide a gear assembly configuration with the advantages listed above that provides righthand as well as lefthand access to the worm to minimize inventory parts, cost, and tooling expenditures.